About a week ago check engine came on and it read Misfire in Cylinder #4. Figured it was my coil over and spark plug. Had them both replaced and didn't help at all. Whenever i press the gas to get up to speed my truck hesitates very bad and stutters, shakes. Even at idling it will do it also. Changed my fuel filter and didn't help. Any idea what to check on next im trying to drive it the least possible till i get it resolved. Thanks for any input. My engine is also a 5.4.

 

3 things to make it run. Air, spark and fuel. You have new coil and plug (spark). Have you check the fuel injector? I'm leaning towards a dirty injector or carboned cylinder (valve etc). You might try a good carbon blaster to see if it improves. BG 44k does that. Just a thought.

 

Im taking it in Tuesday to get the fuel system tested. I looked at the BG 44K is it the same as Seafoam been using that for years in my truck. Every oil change i would use seafoam.

 

No not the same as seafoam. Much better,

 

Good to know, can i go to any auto parts store and grab it or do i need to order it? On another subject have you ever heard of Royal Purple Purple Ice? Was at autozone and happened to see it its an additive for the radiator. Just had mine flushed and didn't know if this stuff was good or just waste of money. Thanks for any input.

 

Waste of money. What color fluid do you have in it? If it's green now, it should be changed every couple years.


There is a thread on where to get BG 44k a page or two back.

 

I dont know the color havent looked at it since i got it flushed a couple days ago. Glad to know it was a waste of money would of cost me $45 for 3 bottles.

 

If the shop only replaced the number 4 coil and plug. Check and see if they replaced the right one. Fords number there cylinders differently than most cars they may have replaced the wrong coil/plug. The number 4 is the back cylinder on the passenger side. The coil should be visible, shiny and new. After that quick check, the injector is suspect, as mentioned, but further diagnostics are needed. I would diagnose the problem before injector/induction cleaning.

 

Taking it in tomorrow morning to get the fuel system tested. Tonight when i was driving for the first time the Check Engine Light started flashing it flashed for about 2 minutes and then stayed steady. Should i be worried that it started flashing?

 

If it is flashing, that means that damage to the cats is possible, and that it should be checked asap.

It is a true idiot light and its intent is to warn you that you have a serious misfire/fueling/emission problem that need immediate attention. By all means, get it checked before you have to spend a bucket load of cash to repair. I hope it isn't too serious, and nothing more than a simple sensor or such. Good luck/